Follower emotes are a great idea, however, currently they hold no real value. A lot of streamers use BTTV/FFZ and have 50 or more emotes for anyone to use in their own chat.
However, rewarding followers that actually come back to your stream a lot would be great! Perhaps it would be possible to give people access to follower emotes in other channels if they spend at least X amount of hrs or X% of a streamer's typical streamtime in their stream (per week or month or whatever).

It rewards coming back, but doesn't take away too much fire away from subs.
It also finally rewards the general viewer, who tends to get overlooked but is very important to the channel's atmosphere. Not everyone can miss a sub's worth of money every month, but this way, simply being part of the community will give them something back.

You could even make this an unlock system that allows a viewer to unlock 1-5 of the emotes outside of the original channel based on their watch time. This way, more active members are rewarded more.